[server] Add multipleStatements support to dbQuery
[server] Add multipleStatements support to dbQuery

Summary: I need this for an upcoming diff

Test Plan: Tested in combination with following diff

Reviewers: atul

Reviewed By: atul

Subscribers: KatPo, palys-swm, Adrian

Differential Revision: https://phabricator.ashoat.com/D1287

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